Automated fiber placement with course trajectory compensation

ABSTRACT

Various automated fiber placement systems and methods are disclosed. The system can determine steerable paths for the application of a composite material over highly contoured surfaces. The system can determine when a course trajectory would violate a steering limitation (e.g., a maximum bendability of the composite material) and can adjust the trajectory to avoid such violations. The adjustment can create gaps between adjacent courses, which can have a generally flared peripheral shape. The system can fill such gaps with subsequent courses of the composite material. Thus, the system can automatically apply composite material to highly contoured surfaces while also avoiding violation of the steering limitations.

BACKGROUND

1. Field

This disclosure relates to producing components using compositematerials, such as by controlling the application of tows of compositematerial during an automated fiber placement operation.

2. Description of the Related Art

Composite materials are used for a variety of high-performanceapplications, such as in aerospace components, automotive parts, andsporting goods A composite material includes at least two constituentmaterials that are combined to produce a material with characteristicssignificantly different than the constituent materials individually.Composite materials typically include a bonding agent or matrix (e.g., aglue or resin) and a substrate or reinforcement (e.g., fiberglass,graphite, carbon-fiber, or other fibrous material). Layers of thecomposite material can be applied to a form that represents the shape ofa component, such as a fuselage, turbine cowling, or wing. The compositematerial is then cured, during which the bonding agent liquefies andflows through the layers of the substrate. The result is a singlecoherent structure with an excellent strength to weight ratio.

Certain composite components are produced by layering the compositematerial onto the form with a hand layup technique. This includescutting flat patterns of composite material and then manually placing orpressing those patterns onto the form. Hand layup requires that theshape of each layer of material be converted from the 3-dimensionalpiece to be produced into a flat pattern, so that the pattern can becut. It also requires great amounts of manual labor to orient and applythe patterns to the form.

An advance over hand layup is tape layup, which includes using a machineto apply wide strips (called “tape”) of composite material to the form.Typically, the tape is between 25 mm and 200 mm wide and is stored on aspool. During application, the tape travels from the spool to acompaction roller, which presses the material onto the form or onto theprevious layers of material. Generally, the compaction roller is mountedon a computer-controlled 5-axis machine (e.g., a CNC machine with thecompaction roller instead of a milling cutter). The tape is pulled ontothe form by the compaction roller being rolled over the surface of theform. To aid in maintaining the tape in place until curing, the tape canbe heated during application and/or can have an adhesive on at least oneside. When the tape is applied to a curved surface, one lateral side ofthe tape experiences compression and the opposite lateral side of thetape experiences tension. This can result in wrinkling, tearing, orwarping of the tape and can be exacerbated by the relatively wide widthof the tape. Thus, tape layup is typically limited to regular, smooth,and/or relatively flat shapes, such as wing surfaces and cylindricalmissile sections.

An advance over tape layup is automated fiber placement (AFP), whichincludes using a machine to apply rows (called “courses”) that are eachmade up of multiple narrow strips (called “tows”) of the compositematerial. For example, each course can include between 8 and 32 tows,and each tow can be between 3 mm and 12 mm wide. Typically, several towspass over a compaction roller (also called a “head”) generally parallelto each other and can be concurrently applied to a form having the shapeof the component to be produced. The compaction roller can be movedrelative to the form to steer the application of the tows to a desiredarea of the form, to provide a desired application pattern of the tows,or otherwise. The application of each tow to the form can be controlledindependent of the other tows. For example, each tow can be individuallystarted, stopped, cut, and/or restarted.

SUMMARY

Typically, the AFP technique allows the composite material to be appliedto forms having a greater degree of contouring than is achievable withtape layup, yet still avoid a flawing event (e.g., wrinkling, tearing,or warping of at least one of the tows). Nevertheless, when applied tocertain highly-contoured shapes, the compression on one side of the towand/or the tension on the opposite side of the tow can still causesufficient stress in the tow to result in a flawing event. For example,wrinkling, tearing, or warping can occur when the tow is applied tocertain three-dimensional dual curve shapes, such as some saddle shapes.

The present disclosure includes an AFP system that can determine whethera flawing event will occur on a particular course and, if so, cangenerate an alternate course path to inhibit or avoid such an event. Forexample, the system can receive information related to the shape andextent of the form, and can generate steering paths (also called“trajectories”) for applying courses of tows to the form. The system cananalyze some or each of the paths to determine whether one or more ofthe tows will be asked to exceed a steering limitation, such beingapplied to a curve with too small a radius of curvature.

If a particular course trajectory is found to violate a steeringlimitation (also called a “steering violation”), the system candetermine an alternate trajectory for that course. Typically, a portionof the alternate trajectory extends generally parallel to a previouscourse, and another portion of the alternate trajectory diverges fromthe previous course, thereby creating a gap between the two courses.Because the gap typically has a substantially triangular or flaredperipheral shape, the alternate trajectory can be called a “flaredpath.” Such a flared path generally avoids, or at least reduces theextent of, the steering violation and thus can reduce the likelihood ofthe flawing event occurring. Certain embodiments can also determinesubsequent courses to fill the gap, thereby avoiding unwanted voids inthe layer of composite material.

Accordingly, various embodiments of the system can determinetrajectories for the application of courses of composite material to theform. The system can determine whether those courses will incur steeringviolations and, if so, can compensate by generating alternatetrajectories. Further, the system can fill the gap formed by suchalternate trajectories by applying additional courses. Suchfunctionality allows the system to automatically apply compositematerial across the extent of highly-contoured surfaces, while stillcomplying with the steering limitations of the composite material.

Neither the preceding summary nor the following detailed descriptionpurports to limit or define the scope of protection. The scope ofprotection is defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The abovementioned and other features of the embodiments disclosedherein are described below with reference to the drawings of theembodiments. The illustrated embodiments are intended to illustrate, butnot to limit, the scope of protection. Various features of the differentdisclosed embodiments can be combined to form further embodiments, whichare part of this disclosure.

FIG. 1 illustrates an automated fiber placement system, which controlsan AFP machine in the application of courses of composite material to aform.

FIG. 1A illustrates a series of courses of composite material on agenerally flat form.

FIG. 1B illustrates one of the courses of FIG. 1A.

FIG. 1C illustrates a head of an AFP machine.

FIG. 1D illustrates a series of the courses of the composite material ona contoured form, the series of courses including parallel path courses,a flared path course, and at least one gap filling course.

FIG. 2 illustrates a method of generating course paths.

FIG. 3 illustrates a method of determining a flared path.

FIG. 3A illustrates a course path that has been determined to violate asteering limitation.

FIG. 3B illustrates an example of a curve that follows a more naturaltrajectory than the course path of FIG. 3A.

FIG. 3C illustrates an example of a flared path along the curve of FIG.3B.

FIG. 4 illustrates a method of filling a gap between a flared path and anon-flared path.

FIG. 4A illustrates an example of a gap filling course path.

FIG. 5 illustrates a method for generating course paths that includescompensation for minor steering violations.

FIG. 6 illustrates an example of tows with minor steering violations.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Various embodiments of an automated fiber placement (AFP) system 10 aredisclosed. As more fully described below, the system 10 can determinesteerable paths for the application of a composite material overcontoured surfaces. The system 10 can determine whether a coursetrajectory will violate a limitation (e.g., the maximum amount thecomposite material can bend without suffering a flaw) and can adjust thetrajectory to avoid such a violation. The adjustment can create gapsbetween adjacent courses, which can have a generally flared peripheralshape. The system 10 can determine subsequent courses of the compositematerial to fill such gaps. Thus, the system 10 can automatically applythe composite material to highly contoured surfaces while also avoidingviolation of the steering limitations.

Overview (FIGS. 1-1D)

With reference to FIG. 1, an embodiment of the system 10 is illustrated.The system 10 can include a computer system, such as a general purposecomputer, that includes a processor and memory. The system 10 canreceive information related to the dimensions or other aspects of acomponent to be produced, such as by accessing a storage element 14(e.g., a database) and/or as an input from a user. The system 10 can usethat information to determine instructions for creating the componentand can output such instructions to an AFP machine 12 and/or can controlthe APF machine 12. The AFP 12 machine can be a conventional AFP machine(e.g., one that is not specifically designed to use the inventionsdisclosed herein). In certain embodiments, the system 10 can includecomputer aided manufacturing (CAM) software 10A, which can interfacewith, and provide instructions to, software on the AFP machine tocontrol application of the composite material. In some implementations,the system 10 includes other software components, such as coursegeneration software 10B, flared path software 10C, and gap fillingsoftware 10D, each of which are discussed in more detail below.

The AFP machine 12 can apply layers (also called plies or sequences) ofcomposite material to a surface representative of a desired shape. Bystacking numerous layers on top of each other on the form, the componentcan be produced. For example, certain components are built-up from atleast 5, 10, 25, 50, or more layers. Typically, the component is thencured (e.g., by heating in an oven) to produce a unified piece.

Generally, each layer is produced by applying several courses 20 (e.g.,rows or swaths) of the composite material to the surface (also called aform). For example, the layer shown in FIG. 1A includes courses 20A-E,with respective centerlines 20A′-20E′. Typically, it is beneficial forthe courses to be generally parallel to each other in a particularlayer. This is because each course of the composite material generallyhas strength along a particular axis (e.g., the longitudinal axis of thecourse), so aligning the courses in generally parallel rows allows thestrength of those courses to work together along the axis. The coursesin different layers can be oriented in different axes, which can aid inproviding strength in many or all directions. For example, a first layercan be oriented at about 0° relative to a reference axis on thecomponent, a second layer can be oriented at about +45°, a third layercan be oriented at about −45°, and a fourth layer can be oriented atabout 90°.

Each course can include several individual tows 22 of the compositematerial. For example, as shown in FIG. 1B, the course 20A includes 12tows, with 6 tows on each side of the centerline 20A′. In variousembodiments, each tow includes fibers (e.g., carbon fibers) impregnatedwith an epoxy resin.

The tows are applied by a head 24 of the APF machine. As shown in FIG.1C, the head 24 has a roller 26 and one or more tow sources 28, such asspools of the tow material. The tow sources 28 feed the tows to theroller, which compresses the tows onto the form as the head 24 and formmove relative to each other (e.g., the head can move and the form canremain stationary, or vice versa). In some embodiments, the head 24activates or energizes the tows during application, such as by applyingheat or UV light.

The head 24 can individually start and stop each of the tows 22. Forexample, as shown in FIG. 1A, certain tows 22 are stopped and restartedin course 20B and all of the tows 22 are stopped and restarted in course20C. This can aid in producing voids in the form, such as for windows orother cavities. The head 24 can include a cutting element to cut the endof a stopped tow. However, the length of a tow typically must be atleast the distance between the cutting element and the head 24. This iscalled the “minimum tow length”.

As noted above, the system 10 can receive information related to thecomponent to be produced and/or the production operation. For example,the system 10 can receive information regarding dimensions related tothe shape and extent of the surface, such as in a matrix. In someembodiments, the information is related to the composite material, suchas the width of a course, the width of a tow, the number of tows percourse, the minimum bending radius for a tow, or otherwise. In someembodiments, the information is stored on the storage element 14 (e.g.,a database). In certain variants, the information is provided as a userinput.

The system 10 uses the information to determine paths for application ofthe courses of composite material over the surface. This can includeproducing a representation of the surface and/or plotting a plurality ofcourses over the extent of the surface. On a flat region, determiningthe course paths is typically fairly straight-forward. This is because,on a flat region, the tows in the course are not required to bend overcontours of the form, so are substantially free of bending stress. Thus,each course can simply be applied parallel to the previous course.However, for contoured regions, determining the course paths can besignificantly more difficult. This is because, as noted above, when thetows 22 are applied to a contoured surface, one lateral side of each towexperiences compression and the opposite lateral side of each towexperiences tension, which causes stress in the tows. If the stress on atow is sufficiently high, a flawing event (e.g., wrinkling, tearing, orwarping of the tow) can occur, which can reduce the strength of theoverall component.

The system 10 can be configured to determine course paths that avoidsuch flawing events. To do so, the system 10 produces and/or analyzescourse paths based on one or more constraints, which are called“steering limitations.” In some embodiments, a steering limitation isthe maximum amount a tow can bend without incurring a flawing event. Forexample, the steering limitation can be the minimum radius a tow can bebent around in a horizontal plane for a certain tow length withoutsuffering a tear or wrinkle. In certain variants, for a tow width ofapproximately 3 mm, the steering limitation can be a radius of at leastapproximately 250 mm and/or less than or equal to approximately 1000 mm,such as 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, valuesbetween the aforementioned values, or other values. In some embodiments,for a tow width of approximately 6 mm, the steering limitation can be aradius of at least approximately 1000 mm and/or less than or equal toapproximately 2500 mm, such as 1100 mm, 1300 mm, 1500 mm, 1800 mm, 2000mm, 2200 mm, 2400 mm, values between the aforementioned values, or othervalues. In some implementations, for a tow width of approximately 12 mm,the steering limitation can be a radius of at least approximately 5000mm and/or less than or equal to approximately 10000 mm, such as 6000 mm,7000 mm, 8000 mm, 9000 mm, values between the aforementioned values, orother values.

The amount of bending that a tow is asked to perform when placed on acurved surface can be expressed as a radius of curvature. For example,for a tow bending on an arc on a plane, the radius of curvature R forthe centerline of the tow can be expressed as:

$R = \frac{W\left( {L + S} \right)}{2\left( {L - S} \right)}$

Where W is the lateral width of the tow, L is the arc length of theoutside of the tow, and S is the arc length of the inside of the tow. Incertain implementations, a steering limitation is the minimum radius ofcurvature that a tow can curve around without incurring a flawing event.For example, for a tow width of approximately 3 mm, the steeringlimitation can be a radius of at least approximately 250 mm and/or lessthan or equal to approximately 1000 mm, such as 300 mm, 400 mm, 500 mm,600 mm, 700 mm, 800 mm, 900 mm, values between the aforementionedvalues, or other values. As another example, for a tow width ofapproximately 6 mm, the steering limitation can be a radius of at leastapproximately 1000 mm and/or less than or equal to approximately 2500mm, such as 1100 mm, 1300 mm, 1500 mm, 1800 mm, 2000 mm, 2200 mm, 2400mm, values between the aforementioned values, or other values. As afurther example, for a tow width of approximately 12 mm, the steeringlimitation can be a radius of at least approximately 5000 mm and/or lessthan or equal to approximately 10000 mm, such as 6000 mm, 7000 mm, 8000mm, 9000 mm, values between the aforementioned values, or other values.

Some embodiments vary the steering limitation with a factor of safety.This can add a buffer between the stress actually experienced by thetows on the plotted paths and the stress the tows could theoreticallytolerate without incurring a flawing event. In some embodiments, thefactor of safety increases the steering limitation value, such as whenthe steering limitation is based on a radius of curvature. In somevariants, the factor of safety decreases the steering limitation value,such as when the steering limitation is based on a minimum bend radiusof the tows. In certain implementations, the factor of safety alters thesteering limitation value by at least about: 5%, 10%, 20%, 30%, 50%,values in between the aforementioned values, or other values. In someembodiments, the factor of safety alters the steering limitation valueby between approximately: 1% and 50%, 5% and 30%, 10% and 20%, or othervalues. The original (e.g., theoretically tolerable) steering limitationplus the factor of safety can be called the “comfortable” steeringlimitation. For example, when the minimum radius of curvature of the towis altered by the factor of safety, the result is called the“comfortable” steering radius for the tow. In various implementations,the maximum amount a tow can bend, the minimum radius of curvature of atow, the factor of safety, and/or the comfortable steering radius areprovided to the system 10 from the storage element 14 and/or as a userinput.

An example of a series of courses on a contoured surface is illustratedin FIG. 1D. For purposes of presentation, alternating courses arecross-hatched. As indicated in the description below, which referencesback to certain aspects of FIG. 1D, the system 10 can determine pathsfor applying courses of the composite material. As shown, the system 10can determine a plurality of parallel course paths, such as when thepaths comply with the steering limitations. As also illustrated, thesystem 10 can provide an adjusted path (a flared path) when a steeringviolation is detected. Because the flared path diverges from theparallel paths, a gap is formed, which the system 10 can provideadditional paths to fill. After the flared path and/or the gap fillingpaths, the system 10 can continue providing additional parallelpaths—until another steering violation is detected and the processbegins again.

Course Generation (FIG. 2)

FIG. 2 illustrates a process 200 of determining one or more coursetrajectories for the application of composite material to a surface. Theprocess 200 may be implemented within the course generation softwarecomponent 10B shown in FIG. 1. In Block 220, the process 200 begins withthe system 10 receiving application information. The information can berelated to the surface to which the composite is to be applied, such asthe dimensional data of the surface, a three-dimensional model of thesurface, or otherwise. The information can also be related to thecomposite material to be applied, such as the type of material beingapplied (e.g., resin impregnated carbon fibers), the width of a course,the width of a tow, the number of tows per course, or otherwise. In someimplementations, the information includes a steering limitation, such asa minimum radius of curvature for an individual tow. The system 10 canreceive the information from the storage element 14, as a user input, ora combination of both.

In Block 222, the process 200 determines an initial course, calledCourse A, on the surface. Course A is along a trajectory that is knownto comply with the steering limitations. For example, Course A may be ona generally flat or gently curved portion of the surface, such that thematerial can be steered over that portion without incurring a failure.In certain embodiments, after Course A has been determined, it can berecorded in the storage element 14.

In Block 224, the process 200 determines whether an additional course isto be applied to the surface adjacent to Course A and in the same layeras Course A. The process 200 ends if the answer is negative, such as ifthe extent of the surface has been covered with courses. However, if theanswer is affirmative, then the process 200 continues to Block 226, inwhich the system 10 plots another course (called Course B) on thesurface. Course B is plotted as adjacent to Course A and generallyparallel to Course A. In some embodiments, Course B is on the left sideof Course A, but in other embodiments, Course B is on the right side ofCourse A.

In Block 228, the system 10 analyzes Course B and determines whether anyof the tows in Course B violate the steering limitation. For example,the system 10 can analyze each tow and determine whether any of the towswould be required to bend or flex more than is allowable. In someembodiments, the system 10 determines whether one or more tows wouldtraverse a curve that is less than the minimum steering radius of thecomposite material.

If no tows violate steering limitation in Block 228, then the process200 proceeds to Block 230, in which Course B is deemed a “safe” courseand/or is recorded in the storage device 14. As shown, the process 200continues to Block 234, in which Course B is renamed Course A. Theprocess 200 then loops back to Block 224 to determine a new Course B.This can allow the system 10 to incrementally determine a plurality ofcourses that are generally parallel to each other and in the same layeras each other. Thus, such a series of courses can be called “parallelpath” courses. Provided the answer to Block 228 continues to benegative, then the process 200 continues adding parallel path coursesacross the surface until the extent of the surface has been covered bythe courses, thereby making the answer to Block 224 negative and endingthe process 200.

An example of the parallel path courses is shown in the right hand sideof FIG. 1D, which is an example of a series of courses on a contouredsurface. For purposes of presentation, alternating courses are shadedand the arrow pointing from right to left indicates the direction ofprogression of each additional course across the surface. As shown,beginning on the far right of the figure, the layer includes Course A,which is a steerable course. The system 10 has generated a Course B thatis just to the left of Course A, as well as generally parallel to and inthe same layer as Course A. Because the system 10 determined that theCourse B did not incur any steering violations, the name of the Course Bwas changed to Course A, and the process continued. Additional coursescontinued to be added were across the width of the surface, with eachadditional course progressing to the left of the previous course.

With reference again to FIG. 2, if at least one tow violates a steeringlimitation in Block 228, then a flawing event is possible and theprocess 200 proceeds to Block 232. To avoid, or at least reduce thechance of, the flawing event occurring, Block 232 can call a sub-routineprocess 300 which creates a flared path course, as is discussed below inconnection with FIG. 3.

In various embodiments, after Block 232, the process 200 continues toBlock 234, in which Course B is renamed Course A. The process 200 thenloops back to Block 224 to determine a new Course B. The loop of Blocks224-234 can be repeated until the extent of the surface is covered withcourses of the composite material, at which point the query to Block 224is negative and the process 200 ends.

Flared Path (FIGS. 3-3C)

FIG. 3 illustrates the sub-routine process 300 for determining a flaredpath for a course of the composite material. The process 300 may beimplemented within the flared path software component 10C shown inFIG. 1. As discussed above, the process 300 applies when the system 10has determined that the Course B determined in Block 226 of the process300 would result in at least one tow violating the steering criteria.

The process 300 begins at Block 320, in which the system 10 analyzes thetow within Course B that is the furthest spaced apart from Course A.This tow, called tow_(far), typically is the tow that is opposite thetow that is directly adjacent to Course A. The process 300 includesdetermining the steering for tow_(far) for the path of Course Bdetermined in Block 226 of the process 200 (generally parallel andadjacent to Course A). As shown in FIG. 3A, tow_(far) can include atleast one steering violation.

As shown in FIG. 3, in Block 322, the system 10 determines the longestsegment of tow_(far) that complies with the steering limitations. Forexample, the system 10 can determine the longest segment along thelongitudinal axis of tow_(far) that does not violate the steeringlimitations. In Block 324, the process 300 includes determining a curvethat includes and/or approximates the aforementioned longest segment oftow_(far).

In Block 326, the system 10 offsets the curve relative to Course A. Forexample, the curve can be laterally offset (e.g., spaced apart) fromCourse A in the direction of Course B. In certain embodiments, the curveis offset by an amount that is a function of the width of Course Band/or the width of tow_(far). For example, the curve can be offset byapproximately ½ of the width of the tow_(far) plus ½ the width of CourseB.

In Block 328, the curve is extended to the edges of the form. An exampleof this is shown in FIG. 3B. Typically, the result of the extended curvewill be a more “natural” path along the surface of the form compared tothe path of Course B determined in Block 226. A “natural” path (alsocalled a “geodesic” path) is a path along a curved surface on which bothedges of a tow are the same length as the tow proceeds across the curvedsurface. A tow will generally assume a natural path if laid on thesurface and allowed to drape on the surface with no guidance.

In Block 330, the system 10 determines a new course trajectory, calledCourse C, that is used in place of Course B. In various embodiments,Course C has the extended curve from Block 328 as its centerline.Typically, Course C has a more natural path than Course B, and is thusmore steerable than Course B. This can avoid, or at least reduce thechance of, the potential flawing event determined in Block 228 of theprocess 200. The process 300 then ends.

In several embodiments, Course C has a flared path. This can include afirst portion that is generally parallel to Course A and a secondportion that diverges from Course A. An example of such a course isshown in FIGS. 1D and 3C. However, the flared path of Course C creates agap between Courses A and C in which composite material is missing. Asshown, the gap can have a generally wedge-shaped or triangularperipheral shape. A process for filling this gap is discussed below.

Filling the Gap (FIGS. 4 and 4A)

In various embodiments, after the process 300, the system 10 calls afurther sub-routine process 400, which is related to filling the gapbetween Course A (the non-flared path course) and Course C (the flaredpath course). In various embodiments, the process 400 involves addingone or more courses of the composite material in the gap. The process400 may be implemented within the gap filling software component 10Dshown in FIG. 1.

As shown in Block 420, the process 400 begins with the system 10determining a new course, called Course D, located in the gap. In someembodiments, Course D is generally parallel to Course C (the flared pathcourse) and adjacent to Course C. Course D can extend from an end ofCourse C (e.g., the edge of the form) to an intersection between CourseD and Course A (the non-flared path course). An example of this is shownin FIG. 4A.

In Block 422, the ends of some or all of the tows in Course D are cut.For example, as shown in FIG. 4A, the system 10 can instruct the AFPmachine to cut the ends of the tows positioned at the intersection ofCourse D and Course A. In some embodiments, the tow ends of Course D arecut such that the composite material of Course D does not overlay thecomposite material of Course A. This can aid in maintaining Courses Aand D in a single layer.

In Block 424, the process 400 determines whether there is additionalspace in the gap that has not yet been filled with composite material,and for which it is desirable to fill that additional space withcomposite material. If all of the space in the gap has been filled, orif the remaining unfilled space in the gap is a region in which nocomposite material is to be applied (e.g., if the remaining unfilledspace is a space for a window or other desirable unfilled region in thelayer), then the process 400 ends.

However, if unfilled space remains in the gap, and composite material isto be applied to that unfilled space, then the process moves to Block426, in which the name of Course D is changed to Course C. The process400 then loops back to Block 420. The process 400 determines a newCourse D, cuts the ends of that new Course D relative to Course A, andqueries again whether there is yet further space in the gap that has notyet been filled with composite material and for which it is desirable tofill that additional space with composite material. The loop of Blocks420-426 can be repeated until the unfilled space in the gap has beenfilled at which point, as noted above, the process 400 ends.

In alternate embodiments, in Block 420, the system determines a Course Dthat is generally parallel to Course A (the non-flared path course) andadjacent to Course A. Course D can extend from an end of Course A (e.g.,the edge of the form) to an intersection between Course D and Course C(the flared path course). In such embodiments, in Block 426, the name ofCourse D is changed to Course A before the process loops back to Block420.

In various embodiments, after the process 400 has ended, the system 10returns to the process 200 discussed above. For example, after theprocess 400 has ended, the system 10 can return to Block 232 and thenproceed to Block 234, in which the name of Course B is changed to CourseA. The process 200 then loops back to Block 224 to determine whetherfurther courses of the composite material are to be applied to thesurface. Thus, the processes 200, 300, and 400, can automaticallydetermine paths for courses, determine when a steering violation willoccur, determine a flared path to avoid such a violation, and fill-in agap left between the flared path and non-flared path courses. This canallow the system 10 to automatically determine steerable courses of thecomposite material across the extent of the surface—even on highlycontoured forms.

Short Steering Violations (FIGS. 5 and 6)

In some embodiments, the system 10 permits minor steering violations inapplying the courses of composite material. For example, in certainvariants, if a course's steering trajectory would subject one or moretows to a curve that is less than the comfortable steering radius of thetows (the minimum radius of curvature of the tows plus a factor ofsafety) yet greater than the minimum radius of curvature of the tows,the system 10 allows the course to follow a parallel path rather than aflared path. This can reduce or avoid applying flared path courses forminor steering violations and/or can reduce or avoid applying of shortlengths of tow, either of which can increase the application rate of thecourses to the surface.

A course of the composite material in the band between the comfortablesteering radius of the tows and the minimum radius of curvature of thetows is said to be in the “danger zone.” This is because the tow isbeing flexed to such an extent that it is encroaching on the bufferprovided by the factor of safety. In some implementations, the system 10permits a tow to be in the danger zone for only a limited length alongthe surface. For example, while in the danger zone, the tow can beapplied to the surface for a length that is less than or equal to about:10 mm, 25 mm, 50 mm, 100 mm, 200 mm, values between the aforementionedvalues, or other values. In some implementations, the length that thetow is allowed to be in the danger zone is provided to the system 10from the storage element 14 and/or as an input from a user.

FIG. 5 illustrates a process 500 that permits minor steering violationsin applying the courses of composite material. The process 500 may beimplemented within the course generation software component 10B shown inFIG. 1. In many aspects, the process 500 is identical to the process 200discussed above. For example, as shown, the process 500 includes Block220 for receiving information related to the surface, the compositematerial to be applied, and one or more limitations. The process 500also includes Block 222, in which the system 10 determines an initialcourse (Course A). The process 500 further includes Block 224, whichdetermines whether additional courses of the composite material are tobe applied adjacent to and in the same layer as Course A. Moreover, theprocess 500 includes Block 226, in which the system 10 determines acourse (Course B) that is generally parallel to and adjacent to CourseA.

As shown, rather than Block 228 in the process 200, the process 500includes a decision logic 528 for determining whether to adjust CourseB. The decision logic 528 begins with Block 528A, which determineswhether the trajectory of Course B would subject one or more tows to acurve that is less than the minimum radius of curvature of the tows. Ifthe answer is affirmative, then the process 500, at Block 232, calls theflared path and gap filling sub-routines 300, 400, as discussed above.

If the determination in Block 528A is negative, then the process 500, atBlock 528B, determines whether the trajectory of Course B would subjectone or more tows to a curve that is less than the comfortable steeringradius of curvature of the tows. If the answer is affirmative, then theprocess 500 moves to Block 528C. In Block 528C, the system 10 determinesthe length of the portions of Course B with a steering radius that isless than the comfortable steering radius. The process 500 then moves toBlock 528D, which determines whether the length of any of the portionsof Course B with a steering radius that is less than the comfortablesteering radius are greater than a length limitation. If the answer isaffirmative, then the process 500 moves to Block 232. However, if thedetermination in either of Blocks 528B and 528D is negative, then theprocess continues to Block 230, which permits Course B to be appliedalong a parallel path. As discussed above, after Block 230 and Block232, the name of Course B is changed to Course A in Block 234. Theprocess then loops back to Block 224.

With reference to FIG. 6, in certain embodiments, a steering radius thatis smaller than a minimum radius (e.g., the comfortable steering radius)may be permitted and/or a parallel path course may be applied. Forexample, a course that includes a tow with a steering radius that issmaller than the minimum radius steering radius is allowed if the lengthof the steering violation is of short duration, such as less than alength limitation LL (e.g., specified by a user). In someimplementations, if an “average” radius of some or each of the tows, asdetermined over the length limitation LL, is greater than the minimumradius, then the course is permitted. This can be the case even thoughthe steering radius of one or more of the tows may briefly drop belowthe minimum radius. An example of this is shown in FIG. 6, in whichlocations with a steering radius that is less than the minimum radiusare marked with an “X.” In that illustrated example, the length of thesteering violation (e.g., the longitudinal length of the course alongwhich the Xs are present) is less than the length limitation LL, so theminor steering violation allowable. Some variants determine the averageradius R with the equation:

$R = \frac{W\left( {L + S} \right)}{2\left( {L - S} \right)}$

Where W is the lateral width of the tow, L is the arc length of theoutside of the tow, and S is the arc length of the inside of the tow. Incertain implementations, a parallel path course will be applied even ifthe radius of one or more of the tows is less than the minimum radius,provided that such a steering violation occurs over a length that isless than or equal to the length limitation LL. In some variants, thelength limitation LL is measured along and/or relative to thelongitudinal centerline of the course (e.g., such as the centerlines20A′-20E′ in FIG. 1A). In certain embodiments, the length limitation LLis a value in the range of between about 100 mm and about 200 mm.

Temperature Compensation

Certain types of composite materials can be affected by temperature.Typically, as the temperature increases the flexibility and/orbendability of the material increases, and as the temperature decreasesthe flexibility and/or bendability of the material decreases. Moreover,the composite material may include an adhesive on the side that contactsthe surface (to aid in maintaining the material in place) that can alsobe affected by temperature. For example, the bonding characteristics ofthe adhesive generally increase as temperature increases.

The tows of composite materials are generally applied to the surface ina heated state, such as by a heating element on the head of the AFPmachine. This can increase the flexibility and/or bendability of thetows and can increase the adhesive characteristics (e.g., tackiness) ofthe adhesive at the time of application to the surface. However, as thetows cool, they can become less flexible and/or bendable and theadhesive can become less tacky. This can result in a flawing event inthe tows that occurs some time period after the initial application. Toavoid such a problem, some implementations of the system 10 cancompensate for changes in temperature. For example, the system 10 canchange the steering limitation by a factor of safety. This can reducethe likelihood of a tow violating the steering limitation after it hascooled. In some implementations, the factor of safety is at least about:5%, 10%, 20%, 30%, 50%, values in between the aforementioned values, orother values of the steering limitation value. In some embodiments, thefactor of safety is between: approximately 1% and approximately 50%,approximately 5% and approximately 25%, approximately 10% andapproximately 15%, values in between the aforementioned values, or othervalues.

Some implementations of the system 10 include one or more temperaturesensors. For example, the system 10 can include sensors that measure theambient temperature, temperature of the form, temperature of one or morespools or otherwise. In some embodiments, the system 10 varies thefactor of safety as a function of temperature. For example, as thetemperature of the form decreases, the factor of safety increases.

Other Features

In various embodiments, the system 10 can include one or more computersor computing devices that implement the various functions describedherein under the control of program modules stored on one or morenon-transitory computer storage devices (e.g., hard disk drives, solidstate memory devices, etc.). Each such computer or computing devicetypically includes a hardware processor and a memory. Where the system10 includes multiple computing devices, these devices may, but need not,be co-located. In some cases the system may be implemented oncloud-based or shared computing resources that are allocateddynamically. The system 10 may be connected to the AFP machine via anetwork connection (wired or wireless) or any other type of link thatsupports communications. In some variants, the system 10 is implementedon the AFP machine 12. The processes and algorithms described herein mayalternatively be implemented partially or wholly in application-specificcircuitry, such as Application Specific Integrated Circuits andProgrammable Gate Array devices. The results of the disclosed processesand process steps may be stored, persistently or otherwise, in any typeof non-transitory computer storage such as, e.g., volatile ornon-volatile storage.

As noted above, the system 10 can receive various information related tothe form, the composite material, or otherwise from the storage element14 and/or as user inputs. In some implementations, the storage element14 includes one or more memory devices, such as flash memory, magneticdisk memory, networked or cloud-based memory, or otherwise. The storageelement 14 can store the information in a variety of forms, such as in adatabase. In certain implementations, the storage element 14 includessome of the information (e.g., the dimensional data of the surface) in acomputer aided design (CAD) format, which the system 10 can receive andinterpret, such as with the CAM software.

The user input can be provided to the system 10 via a user interface. Insome embodiments, the user interface includes a graphical userinterface, such as an interface implemented on a special or generalpurpose computer. In certain variants, the user interface includes akeypad and/or buttons operated by the user. For example, the user canprovide the minimum steering radius, the comfortable steering radius,and/or the factor of safety by entering such data on a keypad (e.g., onthe AFP machine).

In certain implementations, the system 10 uses a three-dimensional modelof the contoured surface of the form to make the various determinationsin the processes 200-500, such as whether a trajectory over the formwill violate a steering limitation. In addition, the system 10 can use athree-dimensional model of the head of the APF machine head and/or thecomposite material to emulate or simulate the actions of the AFP machinein applying the tows to the form. In some embodiments, the system 10(e.g., the processes 200-500) can generate a map or instruction set forapplying the courses of composite material to the form. Suchinstructions can be recorded on the storage element 14 or otherwise. Incertain variants, the system 10 interfaces with and/or controls the AFPmachine. For example, the system 10 can output the instruction set tothe AFP machine to instruct the AFP machine on how to apply the coursesto the form, such as by providing the AFP machine the order andarrangement of the courses. In various embodiments, the system 10instructs the AFP machine where and/or when to move the head. In someimplementations, the system 10 can receive inputs from the AFP machine,such as data indicating the status of an application operation, whetheran application operation was successfully performed, or otherwise.

In some embodiments, the system 10 is configured to operate withoutinterfacing and/or controlling the AFP machine. For example, the system10 can generate and/or simulate the application of course paths on theform, without sending (e.g., directly or immediately) such course pathsto the AFP machine. This can allow information related to of thecomposite material application procedure (e.g., the number of parallelpath courses, number of flared path courses, estimated time required toapply the material to the form, etc.) to be determined without actuallyapplying the material to the form. Such simulation can also facilitateplanning for the manufacture of the component, such as by determiningthe amount of composite material required to produce the component, thelength of time the AFP machine will be occupied producing the component,etc.

The system 10 can be operated iteratively, such as by generating aseries of course paths based on a set of constraints (e.g., the contoursof the form, the steering limits, etc.) and then generating anotherseries of course paths based on adjustments to the constraints. This canallow the effect of the constraints to be assessed. For example, agenerated series of course paths can show that a particular curve orcombination of curves on the form is causing flared paths to be created,which in turn is causing an increase in the total time needed to producethe part. Such a curve or combination of curves can be adjusted, andanother series of course paths can be generated to assess effect of theadjustment (e.g., whether the number of flared paths was reduced). Thiscan allow the system 10 to be used to increase the manufacturability ofthe component, manufacturing efficiency, or otherwise. In variousembodiments, after a particular series of course paths and correspondingconstraints have been found acceptable (e.g., by a user), such coursepaths can be stored on the storage element 14 and/or sent asinstructions to the AFP machine.

Summary

Although the systems and methods have been disclosed in the context ofcertain embodiments and examples, it will be understood by those skilledin the art that the systems and methods extend beyond the specificallydisclosed embodiments to other alternative embodiments and/or uses ofthe embodiments and certain modifications and equivalents thereof.Various features and aspects of the disclosed embodiments can becombined with or substituted for one another in order to form varyingmodes of the conveyor. The scope of this disclosure should not belimited by the particular disclosed embodiments described herein.

Certain features that are described in this disclosure in the context ofseparate implementations can also be implemented in combination in asingle implementation. Conversely, various features that are describedin the context of a single implementation can also be implemented inmultiple implementations separately or in any suitable subcombination.Moreover, although features may be described above as acting in certaincombinations, one or more features from a claimed combination can, insome cases, be excised from the combination, and the combination may beclaimed as any subcombination or variation of any subcombination.

Moreover, while operations may be depicted in the drawings or describedin the specification in a particular order, such operations need not beperformed in the particular order shown or in sequential order, and alloperations need not be performed, to achieve the desirable results.Other operations that are not depicted or described can be incorporatedin the example methods and processes. For example, one or moreadditional operations can be performed before, after, simultaneously, orbetween any of the described operations. Further, the operations may berearranged or reordered in other implementations. Also, the separationof various system components in the implementations described aboveshould not be understood as requiring such separation in allimplementations, and it should be understood that the describedcomponents and systems can generally be integrated together in a singleproduct or packaged into multiple products. Additionally, otherimplementations are within the scope of this disclosure.

Conditional language, such as “can,” “could,” “might,” or “may,” unlessspecifically stated otherwise, or otherwise understood within thecontext as used, is generally intended to convey that certainembodiments include or do not include, certain features, elements,and/or steps. Thus, such conditional language is not generally intendedto imply that features, elements, and/or steps are in any way requiredfor one or more embodiments.

Conjunctive language, such as the phrase “at least one of X, Y, and Z,”unless specifically stated otherwise, is otherwise understood with thecontext as used in general to convey that an item, term, etc. may beeither X, Y, or Z. Thus, such conjunctive language is not generallyintended to imply that certain embodiments require the presence of atleast one of X, at least one of Y, and at least one of Z.

Some embodiments have been described in connection with the accompanyingdrawings. Components can be added, removed, and/or rearranged. Further,the disclosure herein of any particular feature, aspect, method,property, characteristic, quality, attribute, element, or the like inconnection with various embodiments can be used in all other embodimentsset forth herein. Additionally, it will be recognized that any methodsdescribed herein may be practiced using any device suitable forperforming the recited steps.

In summary, various embodiments and examples of automated fiberplacement systems and methods have been disclosed. Although the systemsand methods have been disclosed in the context of those embodiments andexamples, it will be understood by those skilled in the art that thisdisclosure extends beyond the specifically disclosed embodiments toother alternative embodiments and/or other uses of the embodiments, aswell as to certain modifications and equivalents thereof. Thisdisclosure expressly contemplates that various features and aspects ofthe disclosed embodiments can be combined with, or substituted for, oneanother. Accordingly, the scope of this disclosure should not be limitedby the particular disclosed embodiments described above, but should bedetermined only by a fair reading of the claims that follow.

The following is claimed:
 1. A system for determining coursetrajectories for the application of tows of composite material to acurved surface using an automated fiber placement machine, the systemcomprising: a non-transitory storage that stores data related to theshape and dimensions of the surface and that stores an indication of asteering limitation; and a computing system comprising one or morecomputing devices, the computing system in communication with thenon-transitory storage and programmed to: access, from thenon-transitory storage, the data related to the shape and dimensions ofthe surface and the indication of the steering limitation; produce,based on the data, a plurality of course trajectories for theapplication of tows over the surface, the trajectories being generallyparallel to each other; determine, for each course trajectory, whetherany of the tows would violate the steering limitation; adjust eachcourse trajectory having a tow that violates the steering limitation,the adjustment avoiding the violation of the steering limitation andcreating a gap between adjacent course trajectories; and produce atleast one additional course trajectory located in the gap.
 2. The systemof claim 1, wherein the steering limitation specifies a maximum amountan individual tow is permitted to bend on the surface.
 3. The system ofclaim 2, wherein the steering limitation corresponds approximately to amaximum amount an individual tow can bend without incurring a flawingevent.
 4. The system of claim 2, wherein the computing system is furtherprogrammed to: receive a comfortable steering limitation; and determine,for each course trajectory, whether a tow would violate the comfortablesteering limitation.
 5. The system of claim 4, wherein the computingsystem is further programmed to: receive a length limitation; determine,for a tow that violates the comfortable steering limitation, the lengthof the portion of the tow that violates the comfortable steeringlimitation; and adjust the course trajectory for those coursetrajectories having a tow in which the length of the portion of the towthat violates the comfortable steering limitation is greater than thelength limitation.
 6. The system of claim 1, wherein, for a particularcourse trajectory having at least one tow that violates the steeringlimitation, the computing system is programmed to adjust the coursetrajectory by: determining a tow in the particular course that islocated laterally farthest from an adjacent and previous course;determining, for the tow located laterally farthest from the adjacentand previous course, the longest segment of the tow that complies withthe steering limitation; determining a curve that approximates thelongest segment of the tow; and plotting an adjusted course trajectoryhaving the curve as the centerline.
 7. The system of claim 1, whereinthe at least one course trajectory located in the gap intersects withanother course, wherein the system is configured to cause the automatedfiber placement machine to use the adjusted and additional coursetrajectories.
 8. The system of claim 1, further comprising the automatedfiber placement machine, wherein the system is configured to cause theautomated fiber placement machine to use the adjusted and additionalcourse trajectories.
 9. Non-transitory computer storage having storedthereon executable program code that directs a computer system toimplement a process that comprises: receiving dimensional data for acontoured surface on which a plurality of courses of composite materialare to be applied, each course comprising a plurality of tows; receivinga steering limitation related to the ability of an individual tow totraverse a curve; determining a trajectory of a first course on thesurface; determining a trajectory of a second course on the surface, thesecond course adjacent to and generally parallel to the first course;analyzing the trajectory of the second course to determine whether anyof the tows in the second course violate the steering limitation; anddetermining an alternate trajectory for the second course in response todetermining that a tow in the second course violates the steeringlimitation, the alternate trajectory complying with the steeringlimitation.
 10. The storage of claim 9, wherein the alternate trajectorycomprises a first portion that is generally parallel to the first courseand a second portion that is non-parallel to the first course
 11. Thestorage of claim 9, wherein the process further comprises filling aportion of a gap with a third course, the gap having a flared peripheralshape and being located between the first course and the second portionof the third course.
 12. The storage of claim 11, wherein the thirdcourse is generally parallel with the second portion of the alternatetrajectory of the second course.
 13. The storage of claim 9, wherein thesteering limitation comprises approximately the minimum radius ofcurvature around which a tow can bend on the surface.
 14. The storage ofclaim 13, wherein the process further comprises: receiving a comfortablesteering limitation; receiving a length limitation; determining that atow in the second course violates the comfortable steering limitation;determining the length of the portion of the tow that violates thecomfortable steering limitation; determining that the length of theportion is greater than the length limitation; and determining analternate trajectory for the second course.
 15. The storage of claim 14,wherein the comfortable steering limitation comprises the minimum radiusof curvature around which a tow can bend plus a factor of safety. 16.The storage of claim 15, wherein the factor of safety is at least 25% ofthe minimum radius of curvature around which a tow can bend.
 17. Amethod of controlling an automated fiber placement machine configured toapply courses of composite material to a form, each course comprising aplurality of tows, the method comprising: receiving informationindicative of the shape and extent of the form; receiving a limitationon the amount an individual tow can be bent when applied to the formwithout incurring a flawing event; producing a plurality of generallyparallel path course trajectories over the form; identifying thosecourse trajectories in which at least one tow violates the limitation;replacing, for those course trajectories in which at least one towviolates the limitation, the parallel path course trajectory with aflared path course trajectory, the flared path course trajectorycreating a gap in relation to a previous course; and producing at leastone additional course trajectory to fill the gap.
 18. The method ofclaim 17, further comprising producing an instruction set of courses.19. The method of claim 18, further comprising instructing the automatedfiber placement machine to apply the courses to the form based on theinstruction set.
 20. The method of claim 17, wherein the additionalcourse trajectory intersects the previous course, and wherein the methodfurther comprises cutting the ends of tows in the additional coursetrajectory at the intersection.